Objectives: To determine the prevalence of symptoms of depression, anxiety and stress among secondary school girls. Methods: A cross- sectional study was carried out on secondary school girls in Abha city, Aseer Region, Saudi Arabia, using the Arabic version of the Depression, Anxiety, and Stress Scale (DASS-42). Results: Of 545 female students recruited in this study, 73.4% had the symptoms of at least one of the three studied disorders; 50.1% had at least two disorders. The prevalence of symptoms of depression, anxiety and stress was 41.5 %, 66.2% and 52.5% respectively. The majority of symptoms were mild to moderate in severity. The scores for depression, anxiety, and stress were positively and significantly correlated. No significant association was found between the girls' sociodemographic characteristics and the scores of the three studied disorders. Conclusion: One of the most important aspects of a primary care physician's care of females is to screen for and treat common mental disorders.